Enhanced flow in agglomerated and bound materials and process therefor

ABSTRACT

In broad terms, this process adds organic material to particulate solids and works the mix. Resolification in a unique way creates improved binding of the particulate solids. The particulate solids are materials such as metal, semi-metal, ceramic, glass, plastic, or rubber, alloy, composite, agglomerate, or other organic. The organic selection should remain solid in handling and may become liquid during compaction. These materials may consist of a liquid, solid or mixture selected from the group consisting of fatty acids; and amides, bisamides, soaps and salts of fatty acids, waxes, resin, oils, hydrogenated fats and oils, polymers, mold release or friction reducing agent. With lubricity enough to enable ejection of a molded compact, flow and adequately low molecular weight and formulation to enable clean burn off if desired. With inputs that may include either pressure, solvents, chemical activation of polymers, or thermal heat; and working so as to enhance the gluing of particulates together and rounding of the agglomerate to provide flowability.

TECHNICAL FIELD

[0001] This invention relates to enhancing the flow of agglomerates andbound materials utilizing organic materials. This invention also relatesto a process for working particulate materials during agglomeration in aunique way.

BACKGROUND OF THE INVENTION

[0002] Agglomeration and binding materials is done to prevent thesegregation of fine and course materials. Graphite or other alloys oralloy precursors in a fine form enhance dispersion within a greatermatrix of ‘iron’ or other principle material or alloys. The particlesize distribution is manipulated to attain desired performance underspecific conditions. The formulation of agglomerates or filler materialentails fabricability and processing considerations in addition toconstituency selection.

[0003] In thermal, solvent, pressured, or activated polymer processing,the management of inputs during agglomeration or binding is critical tothe achievement of a sound composite or agglomerate with out degradingthe organic constituent. Insufficient inputs can cause poor bonding,porosity and irregular deposit configuration and segregation. Theseconditions are precursor to the formation of agglomerates having agreater disparity in compositions. Excess inputs produce dilution,fragmenting, and oxidation of the organic constituent. The effects ofinsufficient inputs on the sintering of the compacts made with theseweak agglomerates or poorly bound materials include greater variation inproduction, distortion, voids, softening, or embrittlement. The effectsof excess inputs during the formation of agglomerates include reductionin the effectiveness of the lubricant or mold release to aid inreduction of particle/particle or agglomerate/ agglomerate frictionduring compaction. Increase in dusting, segregation in handling; anddecrease in effectiveness in ejecting the compact from the die areproblems that often occur during processing. They occur after pressingof the compact or during slurry filling of the cavities. They are theprimary purpose of the mold release or lubricant in the first place.

[0004] With the aforementioned defined process, adding the workingduring processing attains the necessary rounded agglomerates; andenhanced flow characteristics.

[0005] The benefits of this greater flow-ability in traditional pressand sinter is enhanced production speed, greater consistency in part topart production, as well as decrease in variation seen over time. Thisconsistency is of paramount importance in decreasing the number of badparts produced in any given manufacturing process using bound oragglomerated materials. Increasing speed of the manufacturing processduring compaction and filling of cavities, decreasing capital equipmentcosts and labors necessary to produce parts also are achieved benefits.

BRIEF SUMMARY OF THE INVENTION

[0006] The composition and process of this invention eliminates theseproblems. In broad terms with particulate solids, adding organicmaterial and working it upon resolidification in a unique way createsimproved binding of the particulate solids. The particulate solids arematerials such as metal, semi-metal, ceramic, glass, plastic, alloy,composite, agglomerate or other organic rubber. The organic selectionshould remain solid in handling and may become liquid during compaction.These materials may consist of a liquid, solid, or mixture selected fromthe group consisting of fatty acids; and amides, bisamides, soaps andsalts of fatty acids; waxes, resins, oils, hydrogenated fats and oils,polymers, resins or mold release or friction reducing agents. Withlubricity enough to enable ejection of a molded compact, flow, anadequately low molecular weight and formulation to enable clean burn offif desired. With inputs that may include either pressure, solvents,chemical activation of the polymers or resins, or thermal heat; andworking so as to enhance the gluing of particulates together androunding of the agglomerate to provide flowability.

[0007] In an example of thermal processing of a sample to be handled atroom temperature, the preferred method makes a mix containing allingredients that are to be used in this binding sequence. I then heatthe mix above the melting point of the organic. As the temperature risesabove the melting point, so does the materials chance for degradationincrease. Keeping it slightly above its melting point for as little timeas possible is a good thing for the organic. On the other hand as weraise the temperature and/or time the viscosity increases. This allows agreater wetting of the particulate surfaces and greater and moreconsistent distribution of the lubricant to be used as a binder.Generally working below the vapor or boiling or the lubricant and aboveits melting point is desirable. Preferably, the range is less then halfthe temperature difference between its boiling or vapor point and itsmelting point. Most preferably, I work as close to the melting point aspossible, while still maintaining a liquid state when working andcooling begins to form the agglomerate. The heated material must beworked with a chilling device with the heat transfer potential to bringthe mix down below its titer or softening point. This returns the binderto a solid. The motion or work forms rounded or more sphericalagglomerates. This enhances the flowability of the agglomerates aftercooling. After the chilling step, the mix can be screened to reduce therange of the agglomerates and create an even more consistent flow.

DETAILED DESCRIPTION OF THE INVENTION

[0008] In thermal processing, the process step of heating the mix meansheating above the melting point of the organic material. The processincludes the steps of using heated material so that upon cooling, itfreezes and “glues the particles together”. By taking heated materialand working it during cooling, the creation of rounded agglomerates ispossible. Extending the subsequent heating and cooling to multiplematerials with tiered melting points allows for paired or coupledpre-alloys to be distributed within the greater bound mix.

[0009] Other methods include the following steps. Multiple bindinglevels using multiple materials with tiered melting points. Examplesused are pre-bound mixes, which will ultimately allow precursors ofcomplex inter-structural alloys to form within the matrix of a component(multi-matrix composites). This allows for paired of coupled pre-alloysto be distributed within a greater bound mix. Using solvents of pressureinstead of heating to force the wetting of the lubricant made binderalso is possible. In addition, I can use chemical activation of thepolymers or resins.

[0010] Solvent activation refers to the organic material dissolved in asolvent with the particulate solids. The preferred process includes thesteps of using solvents so that upon evaporation of the solvent, itglues the particles together. This process takes materials that have hadthe organic portion dispersed in a solvent and works them duringevaporation of the solvent in such a way as to form roundedagglomerates.

[0011] Pressured material refers to either adding or reducing thepressure of an organic material with particulate solids. At atmosphericpressures, this process includes the steps of using pressured materialso that it phase changes into a liquid or vapor and re-solidifies uponreturning to atmospheric or room pressure “gluing the particlestogether”. The process also includes taking pressured material andworking it during re-solidification or its return to atmospheric or roompressure in such a way that the creation of rounded agglomerates ispossible.

[0012] Chemically activating the polymers or resins and working the mixalso forms rounded agglomerates.

[0013] The organic lubricant or binder may consist of a liquid, solid,or mixture selected from the group consisting of fatty acids; andamides, bisamides, soaps and salts of fatty acids; waxes, resins, oils,hydrogenated fats and oils, polymers or mold release or frictionreducing agent. With lubricity enough to enable ejection of a moldedcompact, flow, an adequately low molecular weight and formulation toenable clean burn off is desired.

[0014] In one aspect, this invention relates to powder metallurgycompositions containing elemental and/or pre-alloyed non-ferrous metalpowders, organic lubricants, with or without flake graphite additive.For example, pre-blended bronze compositions are commonly used forself-lubricating bearing and bushings, oil impregnated bearings formotor use, household appliances, tape recorders, video cassetterecorders, etc. In commercial powder metallurgy practices, powderedmetals are converted into a metal article having virtually any desiredshape.

[0015] The metal powder is firstly compressed in a die to form a “green”pre-form or compact having the general shape of the die. The compact isthen sintered at an elevated temperature to fuse the individual metalparticles together into a sintered metal part having a useful strengthand yet still retaining the general shape of the die in which thecompact was made. Metal powders utilized in such processes are generallypure metals, or alloys or blends of these and sintering will yield acomponent having between 60% and 95% of the theoretical density. Ifparticularly high-density low porosity is required, then a process suchas hot isostatic pressing, explosive compaction, or double mold doublesinter may be utilized. Bronze alloys used in such processes comprise ablend of approximately 10% of tin powder and 90% of copper powder andaccording to one common practice the sintering conditions for the bronzealloy are controlled that a predetermined degree of porosity remains inthe sintered part. Such parts can then be impregnated with oil underpressure or vacuum to form a so-called permanently lubricated bearing orcomponent. These parts have found wide application in bearing and motorcomponents in consumer products and eliminate the need for periodiclubrication of these parts during the useful life of the product. Solidlubricants can also be included and these are typically waxes,metallic/non-metallic stearate, graphite, lead and tin alloys,molybdenum disulfide and tungsten disulfide, bismuth as well as manyother additives. However, the powders produced for use in powdermetallurgy have typically been commercially pure grades of copper powderand tin powder which are then mixed in the desired quantities.

[0016] For many metallurgical purposes, the resulting sintered producthas to be capable of being machined that is to say it must be capable ofbeing machined without either “tearing” the surface being machined toleave a “rough” surface or without unduly blunting or binding with thetools concerned. It is the common practice for a proportion of lead,tin, MnS, or other solid lubricant up to 10% to be introduced to aid andimprove the machine-ability of the resulting product.

[0017] Metallic binders such as cobalt, zirconium, tin, copper, silver,gold, bismuth can hold higher melting point particulates together into acomposite. Application can be whole particles having a single chemistry,examples being a metallic carbide of tungsten, silicon, titanium, orother hard materials such as diamond like materials, glasses, oxides,nitrates, and other similar substances; or processed particles having adeposition, film, or surface modification. Examples of this second classof materials include a material which is only moderately hard, having ahardness which in itself is not sufficient. In this case, a deposition,film or surface modification may be used examples being electroplating,ion beam, physical or chemical vapor deposition. Besides obtaining agreater particle surface hardness, a composite of greater hardness canbe achieved utilizing materials made with particles processed in thisway. Among the materials of greater hardness that can be deposited bymeans of a physical or chemical vapor deposition includesilicon-carbides, the carbides and nitrites of metals especiallytransition metals including and the form of carbon with cubiccrystallographic lattice and others such as cubic-boron-nitrate. Thereare many known processes for the physical or chemical deposition byvapor which can be used to obtain a layer of silicon carbide, or ofother material of greater hardness. Among these processes, the ones thatare particularly advantageous are CVD, PVD, PE-CVD. Once againagglomerates can be formed utilizing either or both of theseparticulates with a metallic binder by adding a organic material,heating the mixture to a temperature above the melting temperature ofthe organic material; maintaining the temperature above the meltingtemperature of the organic material; and slowly cooling andsimultaneously working the heated mixture to below the softening pointof the organic material to coat the particles with the metal binder andform rounded agglomerates.

[0018] One example is the case of thermal activation of metallic binderssuch as cobalt, and zirconium is used with tungsten carbide. It isuseful to disperse the binder as a film over the particles andagglomerate to prevent segregation. Intermediary agglomeration usingorganic material may be used to “glue the metallic binders to the hardmaterials”. Adding an organic material and heating the mixture to atemperature above the melting temperature of the organic material;maintaining the temperature above the melting temperature of the organicmaterial; and slowly cooling and simultaneously working the heatedmixture to below the softening point of the organic material formsrounded agglomerates of the cooled mixture. The difficulty of handlingand transferring hard, coarse and sharp materials is greatly aided byuse of rounding agglomerates made from these products. After the organicmaterial aids in reducing particle/particle or agglomerate/agglomeratefriction and the parts release from the mold. Subsequent processing willreduce the organic materials and melt the metallic binder so that itglues the hard particles together in the compact.

[0019] In another aspect, this invention relates to powder metallurgycompositions containing elemental and/or pre-alloyed non-ferrous metalpowders with organic lubricants. For example pre-blended aluminumpowders are used for their ability to oxidize, workability,conductivity, as pigments and glitters, or relative lightness whencompared to steel. Uses include fuel cells, household appliances,pigments, and foils, sprayed onto plastic to decrease permeability orescape of rare gases, or decrease the introduction of air into productssuch as food. In commercial powdered metallurgy practices flame spray orconversion into a metal article having virtually any desired shape.

[0020] In conventional press and sinter manufacturing the powder oragglomerates are firstly compressed in a die to form a “green” pre-formor compact having the general shape of the die. The compact is thensintered at an elevated temperature to fuse the individual agglomeratesor metal particles together into a sintered metal part having a usefulstrength and yet still retaining the general shape of the die in whichthe compact was made. Metal powders utilized in such a processes aregenerally pure metals, or alloys or blends of these and sintering willyield a component having between 60% and 95% of the theoretical density.If particularly high-density low porosity is required, then processessuch as hot isostatic pressing or explosive compaction may be required.

[0021] Aluminum alloys used in such processes comprise a blend ofaluminum with one or more other elements or alloys such as boron,bismuth, chromium, copper, iron, magnesium, sodium, nickel, lead,silicon, tin, strontium, titanium, zinc, zirconium.

[0022] The cooling or chilling of this invention may vary widely.Typically the cooling depends upon the melting and softening temperatureof the organic material. I prefer that the cooling be as rapid aspossible. Often, the cooling occurs in less than one minute and could beonly a few seconds. However, the cooling may take as long as a fewminutes; e.g. up to 5 minutes. Cooling may even take hours or daysdepending upon the materials.

EXAMPLE I

[0023] In attempting to mold a cam shaft cover, weight 24.0 grams withAlcoa 201 AB and holding a 0.40 gram weight tolerance, the following wasobserved.

[0024] Alcoa 201 AC is a blend comprised of #1202 Aluminum which is airatomized in Texas; #3014 a 50/50 copper/Aluminum master alloy is alsoatomized in Texas; elemental magnesium, and Acrawax C atomized as alubricant. The blend contains Min Max #1202 aluminum 93.60% 98.70% #301450/50 aluminum/copper  0.25%  4.4% Magnesium  0.5%  1.0% With organiclubricant  1.5% Trade name Acrawax aka N,N′-Ethylenebisstearamide 65%\N,N′-Ethylenepalmitamide 35% > Fatty Acid (C14-18) 2%/ Mesh size ˜5Material +50 +100 +200 +325 −325 microns 1202 0.2% 18-22% 26-29% 16-20%27-40% Aluminum max 3014 50/50 0.2% 75-90% copper/alum. max Magnesium 100% Acrawax  100% 50% Alcoa 201 AB as received Alcoa 201 AB ProcessedPress Grams of variation For agglomeration and flow Speed in set of 30Grams of variation in group of 30 7-8 .58 10 6.07 .22 14 .31 20 .44

[0025] The mix was heated in the chamber in inert atmosphere to atemperature above the melting point of the Acrawax in this case 180° C.for 5 minutes (Acrawax melts at 145° C.). Acrawax has a boiling point ofabout 415° C. Working the material during cooling produced roundedagglomerates. The working and cooling was carried out for a period oftime less than 1 minute. Acrawax is a registered trademark of Glyco Inc.

EXAMPLE II

[0026] Another example of a sample holding—100 mesh of Ampal was madeaccording to the procedure of Example I. This was a standard operatingsize so no changes were required to production. The blend contains MinMax Aluminum 93.60% 98.70% Copper  3.6%  4.0% Magnesium  0.8%  1.2%Silicon  0.65%  0.9% With organic lubricant  1.5% Trade name Acrawax akaN,N′-Ethylenebisstearamide 65%\ N,N′-Ethylenepalmitamide 35% > FattyAcid (C14-18) 2%/ Mesh size ˜5 Material +50 +100 +200 +325 −325 micronsAluminum 1.0% 25-45 30-50 20-40 max Copper 100% 18-24 Magnesium 100%18-24 Silicon 100% 18-24 Acrawax 100% 5-6 Ampal 2712 processed Foragglomeration and flow Press Speed Grams of variation in group of 30 10.18 14 .16 20 .22

EXAMPLE III

[0027] A metallurgic bronze powder system comprised of 90% elementalcopper and 10% elemental tin was pre-alloyed, atomized and reduced to apowder. The bronze powder and Acrawax-C atomized the lubricant to bemade a binder, were loaded into a crucible or melting chamber. The mixwas heated in the chamber in inert atmosphere to a temperature above themelting point of the Acrawax in this case 180 C. for a 5 minutes(Acrawax melts at 145 C.). Working the material during cooling producedrounded agglomerates.

[0028] The results show a greater consistency of die filling due tobinding and flow-ability of the mix. Larger particles usually accompanyhigher permeability allowing for greater flow rates. Agglomerate shapedictates the mixes free motion. The agglomerate ability to roll pastother agglomerated particles.

[0029] The results also show binding retards sifting segregation andfacilitates greater homogeneity of alloy distribution regardless ofparticle size. This narrows the range of strength of a compact asmeasured across a narrow cross-section hence increasing strength asmeasured from the lesser number. Less distortion of deformation of thecomponent also is seen after sintering.

[0030] Multiple pre-bound materials mixed together to allow for creationof alloy pins, inclusions, nodes and structure within a greatercomponent is also possible, in addition to multiple matrix components.

[0031] The process has less dusting which helps with equipment uptimedue to cleanliness, consistency of die filling, housekeeping, health,benefits due to reduction of nuisance dust and the reduction ofpotential explosions due to air borne oxidizing or reactive materials.The agglomerates may also be ionized facilitating transfer to or from acharged target.

[0032] Lubricant as a binder, reduction of particle/particle oragglomerate/agglomerate friction during compaction and reduction of diewall friction during ejection occurs, over a process using lesslubricant and more binder. Indications are that typicallycompressibility is decreased slightly, the lubricant is now fixed by theprocess and not free flowing. If the temperature of the tools are belowthe melting point of the bound lubricant and it achieves liquid stateduring compaction; compressibility is restored as the lubricant isdislocated and the bound lube is squeezed out to the die wall where itmay better aid in ejection after compaction. These relatively chilledtools must freeze the binder and with subsequent relative coolingprotect the part from free mix sticking to the part.

[0033] In addition to these embodiments, persons skilled in the art cansee that numerous modifications and changes may be made to the aboveinvention without departing from the intended spirit and scope thereof.

1. A process for producing rounded agglomerates comprising the steps ofproviding a mixture of particulate solids and organic material, thermal,solvent, pressured, or chemical activated processing critical to theachievement of a sound composite or agglomerate without excessivelydegrading the organic material, and working during processing necessaryto form rounded agglomerates; and attain enhanced flow characteristics.2. A process for producing rounded agglomerates comprising the steps ofproviding a mixture of particulate solids and organic material; heatingthe mixture at a temperature above the melting temperature of theorganic material; maintaining the temperature above the meltingtemperature of the organic material; and slowly cooling andsimultaneously working the heated mixture to below the softening pointof the organic material to form rounded agglomerates of the cooledmixture.
 3. A process according to claim 2 wherein the particulatesolids is metal, semi-metal, ceramic, glass, plastic, rubber, alloy,composite, agglomerate or other organic thereof.
 4. A process accordingto claim 2 wherein the heating is maintained at a temperature below theboiling point of the organic material.
 5. A process according to claim 4wherein the heating is maintained at a temperature below the vapor pointof the organic material.
 6. A process according to claim 5 wherein theheating is maintained at a temperature below less than one half of therange between the vapor point and the melting point of the organicmaterial.
 7. A process according to claim 6 wherein the heating ismaintained at a temperature below less than one quarter of the rangebetween the vapor point and the melting point of the organic material.8. A process according to claim 7 wherein the heating is maintained at atemperature below less than one tenth of the range between the vaporpoint and the melting point of the organic material.
 9. A processaccording to claim 8 wherein the heating is maintained at a temperatureslightly above the melting point of the organic material.
 10. A processaccording to claim 2 wherein the working and cooling are carried out fora period of time of 5 minutes or less.
 11. A process according to claim2 wherein the working and cooling are carried out for a period of timeof less than one minute.
 12. A process according to claim 2 wherein theworking and cooling are carried out rapidly.
 13. A process according toclaim 2 wherein the production of rounded agglomerates comprises thesteps of providing a mixture of particulate solids; heating the mixtureto a temperature above the melting temperature of an organic material;then adding the organic material maintaining the temperature of theparticulates above the melting temperature of the organic material; andslowly cooling and simultaneously working the heated mixture to belowthe softening point of the organic material to form rounded agglomeratesof the cooled mixture.
 14. A process according to claim 2 wherein theheating is maintained at a temperature below the boiling point of theorganic material.
 15. A process according to claim 13 wherein theheating is maintained at a temperature below the vapor point of theorganic material.
 16. A process according to claim 13 wherein theheating is maintained at a temperature below less than one half of therange between the vapor point and the melting point of the organicmaterial.
 17. A process according to claim 13 wherein the heating ismaintained at a temperature below less than one quarter of the rangebetween the vapor point and the melting point of the organic material.18. A process according to claim 13 wherein the heating is maintained ata temperature below less than one tenth of the range between the vaporpoint and the melting point of the organic material.
 19. A processaccording to claim 13 wherein the heating is maintained at a temperatureslightly above the melting point of the organic material.
 20. A processaccording to claim 1 wherein the production of rounded agglomeratescomprises the steps of providing a mixture of particulate solids andorganic material; dissolving the organic material in a solvent; andsimultaneously working the mixture as the solvent is allowed toevaporate solidifying the organic material and forming roundedagglomerates.
 21. A process according to claim 1 wherein the productionof rounded agglomerates comprises the steps of providing a mixture ofparticulate solids; dissolving an organic material in a solvent, thenadding the organic material to the mixture of particulate solids; andsimultaneously working the mixture as the solvent is allowed toevaporate solidifying the organic material and forming roundedagglomerates.
 22. A process according to claim 1 wherein the productionof rounded agglomerates comprises the steps of providing a mixture ofparticulate solids; dissolving the organic material in a solvent, thenadding the particulate solids to the dissolving organic material andsolvent; and simultaneously working the mixture as the solvent isallowed to evaporate solidifying the organic material and formingrounded agglomerates.
 23. A process according to claim 1 wherein theproduction of rounded agglomerates comprises the steps of providing amixture of particulate solids and solvent, then adding the organicmaterial to the mixture of particulate solids and solvent; dissolvingthe organic material in a solvent; after the organic material isdissolved simultaneously working the mixture as the solvent is allowedto evaporate solidifying the organic material and forming roundedagglomerates.
 24. A process according to claim 1 wherein the productionof rounded agglomerates comprise the step of providing a mixture ofparticulate solids and organic material; changing pressure enough toallow the organic material to phase change to a liquid or vapor, thenrestoring pressure and simultaneously working the mixture as the organicmaterial solidifies forming rounded agglomerates.
 25. A processaccording to claim 1 wherein the production of rounded agglomeratescomprises the steps of providing a mixture of particulate solids and apolymer or resin; chemically activating the polymer or resin whilesimultaneously working the mixture so as to form rounded agglomerates.26. A process according to claim 1 wherein the production of roundedagglomerates comprises the steps of providing a mixture of particulatesolids and/or pre-agglomerated particulates and organic material;heating the mixture at a temperature above the melting temperature ofthe organic material, and below the melting point of the previousorganic used in making the pre-agglomerated particulates; maintainingthe temperature above the melting temperature of the most recently addedorganic material, and below the melting point of the previous organicused in making the pre-agglomerated particulates; and slowly cooling andsimultaneously working the heated mixture to below the softening pointof the organics materials to form rounded agglomerates of the cooledmixture.
 27. A process according to claim 1 wherein the production ofrounded agglomerates comprise the steps of providing a mixture ofparticulate solids and/or pre-agglomerated particulates; heating themixture to a temperature above the melting temperature of an organicmaterial that is to be introduced, but allow that used in making thepre-agglomerated particulates; then adding this new organic materialmaintaining the temperature of the particulates above the meltingtemperature of the most recently added organic material; and slowlycooling and simultaneously working the heated mixture to below thesoftening point of the organic materials to form rounded agglomerates ofthe cooled mixture.
 28. A process according to claim 1 wherein theproduction of rounded agglomerates comprise the step of providing amixture of particulate solids and/or pre-agglomerated particulates andorganic material; dissolving the new organic material in a solvent inwhich the organic used in making the pre-agglomerates is lessdispersible or dissolvable; and simultaneously working the mixture asthe solvent is allowed to evaporate solidifying the organic material andforming rounded agglomerates.
 29. A process according to claim 1 whereinthe production of rounded agglomerates comprise the steps of providing amixture of particulate solids and/or pre-agglomerated particulates andorganic material; changing pressure enough to allow the newly addedorganic material to phase change to a liquid or vapor without allowingthe organic material used to manufacturing the pre-agglomerates to phasechange, then restoring pressure and simultaneously working the mixtureas the organic material solidifies forming rounded agglomerates.
 30. Aprocess according to claim 1 wherein the production of roundedagglomerates comprises the steps of providing a mixture of particulatesolids and/or pre-agglomerated particulates and polymer; chemicallyactivating the polymer while having little effect on the organicmaterial used in the manufacture of the pre-agglomerates whilesimultaneously working the mixture so as to form rounded agglomerates.31. A product produced according to the process of claim 1.